8. Steve Cohen

Point72

Net worth: $13 billion

Age: 62

Country: US

Industry: Hedge funds

Source of wealth: Self-made; Point72 Asset Management

Steve Cohen for years ran SAC Capital, one of the most successful hedge funds ever. Cohen was forced to shut down SAC after the firm pleaded guilty to insider trading charges. He launched Point72 Asset Management and started taking outside capital in 2018 after running it previously as a family office. He now manages $13 billion.

Earlier this year, a female employee, Lauren Bonner, filed a lawsuit alleging widespread gender discrimination at the fund, including stark wage discrepancies between men and women for the same work. Doug Haynes, the firm's former president and a former McKinsey executive who was named in the suit, left soon after. Bonner's lawsuit was dismissed in federal court last week, and will now be arbitrated.

6. Carl Icahn

REUTERS/Jeff Zelevansky

Net worth: $16.3 billion

Age: 82

Country: US

Industry: Investments

Source of wealth: Self-made; Icahn Enterprises

Carl Icahn has made a lifelong habit and lucrative career out of agitating undervalued and poorly managed companies to change their ways. Since founding his own investment firm in 1968, Icahn has become one of the most powerful people in finance, investing in scores of high-profile companies, including RJR Nabisco, Philips Petroleum, Viacom, Marvel, Time Warner, Netflix, and Herbalife.

Icahn Enterprises now has around $8 billion in assets under management.

5. Abigail Johnson

Abigail Johnson has served as CEO of mutual fund giant Fidelity Investments since 2014, when she took over from his father Ned Johnson III.

Her grandfather the company in 1946.

Johnson owns around 24.5% stake of the firm, which manages $2.5 trillion.

Johnson, who is the first woman to run Fidelity, is known for being very private. Earlier this year, she made a rare speech in an effort to address inappropriate workplace conduct like sexual harassment at Fidelity.

4. Ray Dalio

Ray Dalio's hedge fund, Bridgewater Associates, is the biggest in the world, managing a portfolio of around $160 billion in global investments.

At the top of his industry and having amassed an enormous fortune, Dalio has more recently focused on giving away money and advice. He's taken the Giving Pledge, committing to donate the majority of his wealth to charity. He's also stared his highly coveted "investment secrets," albeit in an unorthodox manner for a hedge funder, in a 30-minute YouTube video. His 123-page, self-published manual on his principles of money management and leadership is also seen as somewhat of a bible among the investment world.

Dalio has always taken a radical approach to management, making everything he and his fund does completely transparent to employees. And it's worked well for him: Bridgewater, while sometimes viewed as "cultish," is one of the most coveted places to work in finance. Dalio has said that he attributes his success, in part, to reminding himself that history repeats itself and keeping track of the decisions he's made that didn't work.

3. James Simons

AP Images

Net worth: $20 billion

Age: 80

Country: US

Industry: Hedge funds

Source of wealth: Self-made; Renaissance Technologies

Before revolutionizing the hedge fund industry with his mathematics-based approach, "Quant King" James Simons worked as a code breaker for the US Department of Defense during the Vietnam War, but was fired after criticizing the war in the press. He chaired the math department at Stony Brook University for a decade until leaving in 1978 to start a quantitative-trading firm. That firm, now called Renaissance Technologies, has more than $57 billion in assets under management among its many funds.

He's given away over $2.7 billion in his lifetime.

9/

2. Thomas Peterffy

Thomas Peterffy, who is frequently considered the father of modern trading, founded discount trading company Interactive Brokers in 1993. He took the company public in 2007, but still owns the majority of it.

Peterffy immigrated to the US from Hungary in 1965 with no money and didn't speak any English. He started off as a software designer and then bought a seat on the American Stock Exchange to trade options in the 1970s. He built a hand-held computer and used it to trade on the floor of the exchange, the first time that had been done.

1. Warren Buffett

Steve Pope/Getty Images

Net worth: $88.3 billion

Age: 88

Country: US

Industry: Diversified investments

Source of wealth: Self-made; Berkshire Hathaway

Berkshire Hathaway CEO Warren Buffett started his prodigious investing career at a young age. As a child he delivered newspapers on his bike, and by 11 the precocious Nebraska native had purchased his first shares in the stock market — Cities Service Preferred at $38 apiece — and sold them for a $5 profit. He was rejected from Harvard Business School, so Buffett went to Columbia Business School instead and learned under iconic value investor Benjamin Graham, who would become a mentor to the budding financier. Buffett worked as a securities analyst in the early-1950s before starting his own investment firm. He bought textile company Berkshire Hathaway in 1969, transforming it into a holding company that would house the many lucrative investments that helped build his massive fortune and earn the nickname "The Oracle of Omaha."

The array of portfolio companies and investments that made him rich may appear random — he's bet on companies including Coca-Cola, American Express, Geico, Fruit of the Loom, Dairy Queen, and General Motors — but they're all cash-generating machines that offer long-term value.

A frugal man with a fondness for junk food, perhaps the most impressive part of Buffett's $88 billion fortune is that it doesn't include $31.5 billion he's already given away. He's good friends with Microsoft cofounder Bill Gates, whom he collaborated with to create the Giving Pledge, a promise for billionaires to give away at least half of their wealth to charity. He's said that he will give away 99% of his wealth.